scholarly journals Localization of Bud2p, a GTPase-activating protein necessary for programming cell polarity in yeast to the presumptive bud site

1999 ◽  
Vol 13 (15) ◽  
pp. 1912-1917 ◽  
Author(s):  
H.-O. Park ◽  
A. Sanson ◽  
I. Herskowitz
Keyword(s):  
Cell Polarity ◽  
Gtpase Activating Protein ◽  
Bud Site

The shape of things to come: morphogenesis in yeast and related patterns in other systems

1995 ◽  
Vol 73 (S1) ◽  
pp. 234-242 ◽  
Author(s):  
Michelle D. Mischke ◽  
John Chant
Keyword(s):  
Cell Polarity ◽  
Site Selection ◽  
Life Cycles ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cell Form ◽  
Number Of Genes ◽  
Molecular Machinery ◽  
To Come ◽  
Bud Site ◽  
Present Understanding

The elaboration of cell form has fascinated biologists for generations. A vast body of literature details the life cycles, anatomy, and developmental programs of many species. The mechanisms responsible for the observed diversity of structure involve polarization, directed growth, and spatial memory. These issues of morphogenesis are currently under study in the budding yeast Saccharomyces cerevisiae and other fungi. In yeast, a number of genes are known that specifically affect either the orientation or the assembly of a polarity axis. These include the bud-site selection genes, BUD1–BUD5, as well as the polarity establishment genes, CDC24, CDC42, CDC43, and BEM1. Members of each of these classes encode elements in signal transduction type pathways. This review examines our present understanding of the molecular machinery responsible for orienting and assembling cell polarity as best understood in S. cerevisiae, and speculates about how similar machinery might function in other fungi. Key words: morphogenesis, polarity, yeast, Saccharomyces, development.

scholarly journals Cell Polarity Protein Spa2P Associates With Proteins Involved In Actin Function InSaccharomyces Cerevisiae

2005 ◽  
Vol 16 (10) ◽  
pp. 4595-4608 ◽  
Author(s):  
Judy L. Shih ◽  
Samara L. Reck-Peterson ◽  
Rick Newitt ◽  
Mark S. Mooseker ◽  
Ruedi Aebersold ◽  
...  
Keyword(s):  
Cell Polarity ◽  
Cell Separation ◽  
Mass Spectrometry Analysis ◽  
Molecular Function ◽  
Spectrometry Analysis ◽  
Tandem Mass Spectrometry Analysis ◽  
Cell Wall Morphogenesis ◽  
Bud Site ◽  
Insight Into

Spa2p is a nonessential protein that regulates yeast cell polarity. It localizes early to the presumptive bud site and remains at sites of growth throughout the cell cycle. To understand how Spa2p localization is regulated and to gain insight into its molecular function in cell polarity, we used a coimmunoprecipitation strategy followed by tandem mass spectrometry analysis to identify proteins that associate with Spa2p in vivo. We identified Myo1p, Myo2p, Pan1p, and the protein encoded by YFR016c as proteins that interact with Spa2p. Strikingly, all of these proteins are involved in cell polarity and/or actin function. Here we focus on the functional significance of the interactions of Spa2p with Myo2p and Myo1p. We find that localization of Spa2GFP to sites of polarized growth depends on functional Myo2p but not on Myo1p. We also find that Spa2p, like Myo2p, cosediments with F-actin in an ATP-sensitive manner. We hypothesize that Spa2p associates with actin via a direct or indirect interaction with Myo2p and that Spa2p may be involved in mediating polarized localization of polarity proteins via Myo2p. In addition, we observe an enhanced cell-separation defect in a myo1spa2 strain at 37°C. This provides further evidence that Spa2p is involved in cytokinesis and cell wall morphogenesis.

scholarly journals A gated relaxation oscillator controls morphogenetic movements in bacteria

2017 ◽  
Author(s):  
Mathilde Guzzo ◽  
Seán M. Murray ◽  
Eugénie Martineau ◽  
Sébastien Lhospice ◽  
Grégory Baronian ◽  
...  
Keyword(s):  
Cell Polarity ◽  
Myxococcus Xanthus ◽  
Dynamic Control ◽  
Relaxation Oscillator ◽  
Critical Importance ◽  
Gtpase Activating Protein ◽  
Wide Range ◽  
Direction Of Movement ◽  
Polarity Reversals ◽  
Cellular Development

SummaryDynamic control of cell polarity is of critical importance for many aspects of cellular development and motility. In Myxococcus xanthus, a G-protein and its cognate GTPase-activating protein establish a polarity axis that defines the direction of movement of the cell and which can be rapidly inverted by the Frz chemosensory system. Although vital for collective cell behaviours, how Frz triggers this switch has remained unknown. Here, we use genetics, imaging and mathematical modelling to show that Frz controls polarity reversals via a gated relaxation oscillator. FrzX, which we newly identify as the primary Frz output, provides the gating and thus acts as the trigger for reversals. Slow relocalisation of the polarity protein RomR then creates a refractory period during which another switch cannot be triggered. A secondary Frz output, FrzZ, decreases this delay allowing rapid reversals when required. This architecture thus results in a highly tunable switch that allows a wide range of motility responses.

Yeast RHO3 and RHO4 ras superfamily genes are necessary for bud growth, and their defect is suppressed by a high dose of bud formation genes CDC42 and BEM1

1992 ◽  
Vol 12 (12) ◽  
pp. 5690-5699 ◽  
Author(s):  
Y Matsui ◽  
A Toh-E
Keyword(s):  
Cell Polarity ◽  
Inhibitory Effect ◽  
High Dose ◽  
Yeast Saccharomyces Cerevisiae ◽  
Bud Formation ◽  
Stabilizing Agents ◽  
Daughter Cells ◽  
Bud Emergence ◽  
Ras Superfamily ◽  
Bud Site

RHO3 and RHO4 are members of the ras superfamily genes of the yeast Saccharomyces cerevisiae and are related functionally to each other. Experiments using a conditionally expressed allele of RHO4 revealed that depletion of both the RHO3 and RHO4 gene products resulted in lysis of cells with a small bud, which could be prevented by the presence of osmotic stabilizing agents in the medium. rho3 rho4 cells incubated in medium containing an osmotic stabilizing agent were rounded and enlarged and displayed delocalized deposition of chitin and delocalization of actin patches, indicating that these cells lost cell polarity. Nine genes whose overexpression could suppress the defect of the RHO3 function were isolated (SRO genes). Two of them were identical with CDC42 and BEM1, bud site assembly genes involved in the process of bud emergence. A high dose of CDC42 complemented the rho3 defect, whereas overexpression of RHO3 had an inhibitory effect on the growth of mutants defective in the CDC24-CDC42 pathway. These results, along with comparison of cell morphology between rho3 rho4 cells and cdc24 (or cdc42) mutant cells kept under the restrictive conditions, strongly suggest that the functions of RHO3 and RHO4 are required after initiation of bud formation to maintain cell polarity during maturation of daughter cells.

scholarly journals MglC, a Paralog of Myxococcus xanthus GTPase-Activating Protein MglB, Plays a Divergent Role in Motility Regulation

2015 ◽  
Vol 198 (3) ◽  
pp. 510-520 ◽  
Author(s):  
Anna L. McLoon ◽  
Kristin Wuichet ◽  
Michael Häsler ◽  
Daniela Keilberg ◽  
Dobromir Szadkowski ◽  
...  
Keyword(s):  
Gene Duplication ◽  
Cell Polarity ◽  
Response Regulator ◽  
Myxococcus Xanthus ◽  
Social Behaviors ◽  
Gliding Motility ◽  
Cellular Polarity ◽  
Gtpase Activating Protein ◽  
Content Type ◽  
Motility Regulation

ABSTRACTIn order to optimize interactions with their environment and one another, bacteria regulate their motility. In the case of the rod-shaped cells ofMyxococcus xanthus, regulated motility is essential for social behaviors.M. xanthusmoves over surfaces using type IV pilus-dependent motility and gliding motility. These two motility systems are coordinated by a protein module that controls cell polarity and consists of three polarly localized proteins, the small G protein MglA, the cognate MglA GTPase-activating protein MglB, and the response regulator RomR. Cellular reversals are induced by the Frz chemosensory system, and the output response regulator of this system, FrzZ, interfaces with the MglA/MglB/RomR module to invert cell polarity. Using a computational approach, we identify a paralog of MglB, MXAN_5770 (MglC). Genetic epistasis experiments demonstrate that MglC functions in the same pathway as MglA, MglB, RomR, and FrzZ and is important for regulating cellular reversals. Like MglB, MglC localizes to the cell poles asymmetrically and with a large cluster at the lagging pole. Correct polar localization of MglC depends on RomR and MglB. Consistently, MglC interacts directly with MglB and the C-terminal output domain of RomR, and we identified a surface of MglC that is necessary for the interaction with MglB and for MglC function. Together, our findings identify an additional member of theM. xanthuspolarity module involved in regulating motility and demonstrate how gene duplication followed by functional divergence can add a layer of control to the complex cellular processes of motility and motility regulation.IMPORTANCEGene duplication and the subsequent divergence of the duplicated genes are important evolutionary mechanisms for increasing both biological complexity and regulation of biological processes. The bacteriumMyxococcus xanthusis a soil bacterium with an unusually large genome that carries out several social processes, including predation of other bacterial species and formation of multicellular, spore-filled fruiting bodies. One feature of the largeM. xanthusgenome is that it contains many gene duplications. Here, we compare the products of one example of gene duplication and divergence, in which a paralog of the cognate MglA GTPase-activating protein MglB has acquired a different and opposing role in the regulation of cellular polarity and motility, processes critical to the bacterium's social behaviors.

scholarly journals The polarity of myxobacterial gliding is regulated by direct interactions between the gliding motors and the Ras homolog MglA

2014 ◽  
Vol 112 (2) ◽  
pp. E186-E193 ◽  
Author(s):  
Beiyan Nan ◽  
Jigar N. Bandaria ◽  
Kathy Y. Guo ◽  
Xue Fan ◽  
Amirpasha Moghtaderi ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Cell Polarity ◽  
Myxococcus Xanthus ◽  
Proton Motive Force ◽  
Gliding Motility ◽  
Cellular Polarity ◽  
Gtpase Activating Protein ◽  
Chemosensory Pathway ◽  
Ras Family ◽  
Ras Family Proteins

Gliding motility in Myxococcus xanthus is powered by flagella stator homologs that move in helical trajectories using proton motive force. The Frz chemosensory pathway regulates the cell polarity axis through MglA, a Ras family GTPase; however, little is known about how MglA establishes the polarity of gliding, because the gliding motors move simultaneously in opposite directions. Here we examined the localization and dynamics of MglA and gliding motors in high spatial and time resolution. We determined that MglA localizes not only at the cell poles, but also along the cell bodies, forming a decreasing concentration gradient toward the lagging cell pole. MglA directly interacts with the motor protein AglR, and the spatial distribution of AglR reversals is positively correlated with the MglA gradient. Thus, the motors moving toward lagging cell poles are less likely to reverse, generating stronger forward propulsion. MglB, the GTPase-activating protein of MglA, regulates motor reversal by maintaining the MglA gradient. Our results suggest a mechanism whereby bacteria use Ras family proteins to modulate cellular polarity.

scholarly journals Identification and characterization of Ral-binding protein 1, a potential downstream target of Ral GTPases.

1995 ◽  
Vol 15 (8) ◽  
pp. 4578-4584 ◽  
Author(s):  
S B Cantor ◽  
T Urano ◽  
L A Feig
Keyword(s):  
Mammalian Cells ◽  
Rho Gtpase ◽  
Binding Protein ◽  
Protein Domain ◽  
Nucleotide Exchange ◽  
Gtpase Activating Protein ◽  
Downstream Target ◽  
Nucleotide Exchange Factor ◽  
Ral Gtpases ◽  
Bud Site

Ral proteins constitute a distinct family of Ras-related GTPases. Although similar to Ras in amino acid sequence, Ral proteins are activated by a unique nucleotide exchange factor and inactivated by a distinct GTPase-activating protein. Unlike Ras, they fail to promote transformed foci when activated versions are expressed in cells. To identify downstream targets that might mediate a Ral-specific function, we used a Saccharomyces cerevisiae-based interaction assay to clone a novel cDNA that encodes a Ral-binding protein (RalBP1). RalBP1 binds specifically to the active GTP-bound form of RalA and not to a mutant Ral with a point mutation in its putative effector domain. In addition to a Ral-binding domain, RalBP1 also contains a Rho-GTPase-activating protein domain that interacts preferentially with Rho family member CDC42. Since CDC42 has been implicated in bud site selection in S. cerevisiae and filopodium formation in mammalian cells, Ral may function to modulate the actin cytoskeleton through its interactions with RalBP1.

BUD2 encodes a GTPase-activating protein for Budl/Rsrl necessary for proper bud-site selection in yeast

Nature ◽  
1993 ◽  
Vol 365 (6443) ◽  
pp. 269-274 ◽  
Author(s):  
Hay-Oak Park ◽  
John Chant ◽  
Ira Herskowitz
Keyword(s):  
Site Selection ◽  
Gtpase Activating Protein ◽  
Bud Site

scholarly journals The LIM domain-containing Dbm1 GTPase-activating protein is required for normal cellular morphogenesis in Saccharomyces cerevisiae.

1996 ◽  
Vol 16 (4) ◽  
pp. 1376-1390 ◽  
Author(s):  
G C Chen ◽  
L Zheng ◽  
C S Chan
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Site Selection ◽  
Yeast Cells ◽  
Gtpase Activating Protein ◽  
Lim Domain ◽  
Yeast Saccharomyces Cerevisiae ◽  
Lim Domains ◽  
Bud Site

Normal cell growth in the yeast Saccharomyces cerevisiae involves the selection of genetically determined bud sites where most growth is localized. Previous studies have shown that BEM2, which encodes a GTPase-activating protein (GAP) that is specific for the Rho-type GTPase Rho1p in vitro, is required for proper bud site selection and bud emergence. We show here that DBM1, which encodes another putative Rho-type GAP with two tandemly arranged cysteine-rich LIM domains, also is needed for proper bud site selection, as haploid cells lacking Dbm1p bud predominantly in a bipolar, rather than the normal axial, manner. Furthermore, yeast cells lacking both Bem2p and Dbm1p are inviable. The nonaxial budding defect of dbm1 mutants can be rescued partially by overproduction of Bem3p and is exacerbated by its absence. Since Bem3p has previously been shown to function as a GAP for Cdc42p, and also less efficiently for Rho1p, our results suggest that Dbm1p, like Bem2p and Bem3p, may function in vivo as a GAP for Cdc42p and/or Rho1p. Both LIM domains of Dbm1p are essential for its normal function. Point mutations that alter single conserved cysteine residues within either LIM domain result in mutant forms of Dbm1p that can no longer function in bud site selection but instead are capable of rescuing the inviability of bem2 mutants at 35 degrees C.

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